Poor services from vodacom

My mom upgraded her phones recently, a consultant by the name Mandy gave us false information regarding the package. She told her that she will be receiving 5gig of data every month and they also gave her homemark vouchers. She realized a few days ago that the data is gone so when she contacted vodacom they told her that the data was only valid for 7 days of which that was not what Mandy told her. Another problem is that when she called homemark to activate the voucher there is no answer and she is using airtime to call now she had to spend a lot of money just to activate a thousand rand voucher. Now vodacom is telling her that there is nothing they can do about the data nor the voucher. When she tried to cancel the contract they told her that she has to pay for the for the period of the contract which is 24 months. I'm so disappointed with vodacom's bad service and she will never upgrade not take another contract with vodacom because they cheated her. What's the point of continuing with the network if she's gonna keep receiving such bad service